Optical system for noise mitigation

ABSTRACT

Configurations for a photonics assembly design and methods for mitigating coherent noise thereof are disclosed. The photonics assembly may include a set of light sources, an optical subsystem that may include a set of optical elements, and a diffusing element. The light emitted by the set of light sources may be different wavelengths and the light may be de-cohered by a phase shifter before being received by the set of optical elements. The diffusing element may be moveable and may be capable of repeating the same positions or set of positions for each beam of light emitted by the set of light sources. By combining the coherent noise mitigation techniques of the moveable diffusing element and the de-cohered light, the photonics system may provide an illumination profile with a specific spatial profile and angular profile on the sample that allows reliable measurement of the sample and coherent noise mitigation.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a nonprovisional of, and claims the benefit under 35U.S.C. 119(e) of, U.S. Provisional Patent Application No. 63/076,249,filed Sep. 9, 2021, the contents of which are incorporated herein byreference as if fully disclosed herein.

FIELD

This disclosure relates generally to systems and methods for coherentnoise mitigation. More particularly, this disclosure relates to a systemwith multiple light sources and optical elements that produce de-coheredlight which forms an asymmetric launch beam.

BACKGROUND

Generally, noise in various types of imaging systems may cause unwantedmodifications of a signal. Noise may degrade images in systems such asmedical ultrasound systems, radar systems, projection systems, or anycoherent imaging system. Noise may cause graininess, granular patterns,or intensity patterns in the measured signal or image. In some examples,noise may significantly interfere with the detection of an opticalsignal, thus the illumination conditions may be designed to mitigatenoise, while maintaining other specifications of the optical system suchas operating speed and size of the optical device or system.

SUMMARY

Embodiments of the systems, devices, methods, and apparatuses describedin the present disclosure are directed to an optical system formitigating coherent noise. Also described are systems, devices, methods,and apparatuses directed to providing de-cohered light that produces anasymmetric launch beam. The optical system may include multiple lightsources that provide de-cohered light via phase shifts, frequencydifferences, and so forth. An optical subsystem may receive the lightfrom the light sources and may substantially collimate the light toproduce a desired intensity profile of a launch beam. The launch beammay include light in the form of light beams from the light sources,where each light beam is incident onto the launch beam with differentangles from one another. The optical system may also include a moveablediffuser to assist in mitigating coherent noise.

In some examples, the present disclosure describes a photonics assembly.The photonics assembly may include a set of semiconductor light sources,each of the set emitting light, a set of output couplers for receivinglight from the set of semiconductor light sources, an optical subsystempositioned to receive the light from the set of output couplers andshape the light, and a diffuser configured to provide the light with acoherent noise state of a set of coherent noise states on a sample,where the diffuser is operative to repeatedly move between at least afirst position and a second position and by moving repeatedly between atleast the first position and the second position, the diffuser mitigatescoherent noise. In some examples, the photonics assembly may include aset of phase shifters positioned to transmit light to each outputcoupler of the set of output couplers and generates de-cohered light, abeam spread of the light emitted by the set of semiconductor lightsources upon exiting the set of semiconductor light sources is between 1and 5 microns in at least one dimension, and a beam spread exiting thediffuser is in a range of 2-4 mm upon incidence on a sample in at leastone dimension. In some examples, the beam spread exiting the diffusermay be approximately 0.5 mm by 2-4 mm.

In some examples, the optical subsystem may include a collimating arraypositioned to receive the light from the set of output couplers and adeflection prism array positioned to receive the light from thecollimating array. In some examples, the optical subsystem may include acollimating array positioned to receive the light from the set of outputcouplers and a diverger array positioned to receive the light from thecollimating array. In some examples, the optical subsystem may include adecentered toroidal lens array positioned to receive the light from theset of output couplers. In some examples, the optical subsystem mayinclude a cylinder lens array positioned to receive the light from theset of output couplers, and a crossed cylinder lens array positioned toreceive the light from the cylinder lens array. In some examples, thediffuser is configured to provide diffused light in an eight degree byeight degree light beam to the sample.

In some examples, the present disclosure describes an optical system.The optical system may include a set of semiconductor light sources foremitting light with multiple light beams, a set of output couplers forreceiving the light from the set of semiconductor light sources, and amoveable diffusing element configured to receive the light from the setof optical couplers, move to a set of positions for each output couplerof the set of output couplers to provide a set of different coherentnoise states corresponding to each output coupler of the set of outputcouplers, and define an illumination profile incident on a sample. Insome examples, the optical system may include an optical subsystemconfigured to receive the light from the set of output couplers and aset of phase shifters for de-cohering the light, where each light beamof the multiple light beams received by the set of output couplers isde-cohered by a corresponding phase shifter of the set of phaseshifters, and each of the set of positions is repeatable. In someexamples, the optical system may include a frequency modulator forde-cohering the light provided by the set of output couplers. In someexamples, the moveable diffusing element is a circular diffuser. In someexamples, the illumination profile is based at least partially on theangle spacing of light received from the optical subsystem. In someexamples, the illumination profile is based at least partially on thetotal range of angles of light incident on the diffuser. In someexamples, the light emitted by each light source of the set ofsemiconductor light sources is a different wavelength.

In some examples, the present disclosure describes a method formitigating coherent noise. The method may include emitting de-coheredlight from a set of light sources, receiving the de-cohered light at anoptical subsystem that generates a desired illumination profile, anddiffusing the desired illumination profile of the de-cohered light usinga moveable diffuser with coherent noise-unique diffuser states for eachlight beam received from each light source of the set of light sources.In some examples, the illumination profile is based at least partiallyon the angle spacing of light received from the optical subsystem, thecoherent noise-unique diffuser states for each light beam may berepeatable, and the total range of angles of light incident on thediffuser. In some examples, emitting the de-cohered light may includegenerating a beam spread that is less than 4 microns upon exiting theset of light sources. In some examples, diffusing the de-cohered lightmay include generating a beam spread of less than 3.2 mm when incidenton a sample. In some examples, emitting the de-cohered light may includephase shifting the de-cohered light. In some examples, each light sourceof the set of light sources is a different wavelength from each other,and diffusing the de-cohered light may include generating a set ofcoherent noise views, wherein a same coherent noise view is generatedfor each wavelength.

In addition to the example aspects and embodiments described above,further aspects and embodiments will become apparent by reference to thedrawings and by study of the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example photonics assembly.

FIG. 2A illustrates an optical system.

FIG. 2B illustrates an optical system.

FIG. 2C is a representation of an illumination profile.

FIG. 2D is a representation of an illumination profile.

FIG. 3A illustrates an example optical subsystem in an optical system.

FIGS. 3B-3C illustrate an example optical system with no diffuser andthe corresponding far field angular separation of light.

FIGS. 3D-3E illustrate an example optical system with a diffuser and thecorresponding non-overlapping far field angular separation of light.

FIGS. 3F-3G illustrate an example optical system with a diffuser and thecorresponding overlapping far field angular separation of light.

FIG. 4 illustrates an example optical subsystem in an optical system.

FIG. 5 illustrates an example optical subsystem in an optical system.

FIG. 6 illustrates an example optical subsystem in an optical system.

FIG. 7 illustrates an example optical subsystem in an optical system.

FIG. 8 illustrates an example optical subsystem in an optical system.

FIG. 9 illustrates an example block diagram of an optical system.

It should be understood that the proportions and dimensions (eitherrelative or absolute) of the various features and elements (andcollections and groupings thereof) and the boundaries, separations, andpositional relationships presented between them, are provided in theaccompanying figures merely to facilitate an understanding of thevarious embodiments described herein and, accordingly, may notnecessarily be presented or illustrated to scale, and are not intendedto indicate any preference or requirement for an illustrated embodimentto the exclusion of embodiments described with reference thereto.

DETAILED DESCRIPTION

Reference will now be made in detail to representative embodimentsillustrated in the accompanying drawings. It should be understood thatthe following description is not intended to limit the embodiments toone preferred embodiment. To the contrary, it is intended to coveralternatives, modifications, and equivalents as can be included withinthe spirit and scope of the described embodiments as defined by theappended claims.

Generally noise, such as random or semi-random noise, may be present invarious types of imaging systems and may cause unwanted modifications ofa signal. In some examples, the noise in the imaging systems may becoherent noise. Noise may degrade images in systems such as medicalultrasound systems, radar systems, projection systems, or any coherentimaging system by causing graininess, granular patterns, or intensitypatterns in the image. Some systems may produce signals with so muchnoise that it may be difficult to determine the measured signal. In someexamples, coherent multipath-interference may be a noise source, oneexample of which may be speckle noise.

In some examples, coherent noise may significantly interfere with thedetection of an optical signal, thus the illumination conditions may bedesigned to mitigate coherent noise, while maintaining otherspecifications of the optical system such as operating speed and size ofthe optical device or system. Different factors may be considered whenmitigating or reducing coherent noise including, but not limited to,illumination conditions within the geometrical specification of thesystem such as intensity profile of the light, the angle distribution orbeam spread angles of the light, and reducing the number of moving partsof the optical system.

In mitigating noise in optical systems, coherent noise may be reducedwithout exacerbating other noise sources in the optical system such asdetector noise and laser noise. In some examples, coherent noise may bereduced by combining the functionality of multiple elements in theoptical system such as a moving diffuser and a phase shifter in theintegrated optics. Additionally, coherent noise may be mitigated byde-cohering multiple light outputs from each other via some temporallyvarying phase relationships. These phase relationships may be from phaseshifters, frequency modulators, and/or from chirping and group delay,any combination thereof, and so forth. In some examples, coherent noisemay be mitigated by each output receiving a slightly differentwavelength. By using these elements in conjunction with observing otherspecifications of the optical system, coherent noise may be mitigated orreduced so that optical signals may be measured more effectively by theoptical system.

Disclosed herein are optical systems, devices, and methods formitigating coherent noise using a moving diffuser and de-cohered lighttogether to produce a predetermined illumination profile incident on thesample. A photonics assembly may include photonics dies that emitmultiple wavelengths. Additionally, the photonics assembly may includethe photonics die(s), outcouplers, optical components that receive lightfrom the photonics die(s), free space optics, and so forth, but does notinclude the sample. The photonics assembly will be described in furtherdetail with reference to FIG. 1 . The light emitted by the photonicsdie(s) may be de-cohered using a phase shifter which may be part of orexternal to the photonics die. The light may be received by an opticalsubsystem that shapes the light and steers the light to a diffusingelement. The optical subsystem may include one or more opticalcomponents as appropriate to achieve the desired shape and beam anglesincident on the diffusing element. In some examples, the opticalsubsystem may shape the light by collimating the light. Generally,shaping the light may include directing the light, focusing the light,collimating the light, other suitable shaping functions, and/or anycombination thereof.

In some examples, the diffusing element may move in one or moredimensions to generate, in conjunction with the de-cohered light beams,unique coherent noise views or coherent noise states and the positionsof the diffusing element may also be repeatable. Coherent noise maycause graininess, granular patterns, or intensity patterns in themeasured signal or image. In some examples, a first light may experiencecoherent multipath-interference that creates coherent noise, where thefirst coherent noise may exhibit a first intensity pattern, which may bea first coherent noise view or coherent noise state. Further to thisexample, a second light may experience coherent multipath-interferencethat creates coherent noise, where the second coherent noise may exhibita second intensity pattern, which may be a second coherent noise view orcoherent noise state. What qualifies as unique coherent noise views orunique (e.g., different) coherent noise states is largely dependent onthe accuracy constraints for a given system design and intended samplecharacteristics, but for the purposes of this application, two or morespectroscopic measurements of a sample have unique noise views or uniquecoherent noise states if they have a correlation coefficient r that isbetween 0 and 0.5 (e.g., between 0 and 0.5 the noise views aredecorrelated from one another). It should be appreciated however, thatsome systems may be designed with a different accuracy constraint (e.g.,r between 0 and 0.4 or r between 0 and 0.3). The correlation coefficientmay be at least partially based on mapping the intensity value of theimage where the bright areas may correspond to high correlation and thedark areas may correspond to low correlation.

As described herein, although the positions or the sets of positions ofthe diffusing element are discussed as repeatable, the positions or thesets of positions may be approximately repeatable and within about a tenpercent variation of the actual position. In some examples, the diffusermay move between a predetermined set of positions repeatedly over thecourse of a measurement. The predetermined set of positions may be arepeating sequence (e.g., 1-2-3-4-1-2-3-4 or 1-2-3-4-4-3-2-1) or apseudo-random sequence (e.g., 1-2-4-1-2-3-1-4 . . . ), and the diffusermay spend equal time at each position. Additionally, in performingmeasurements, there may be some inaccuracy between a target position ofthe diffuser and the actual position. The tolerances may be dependent onan individual system and may vary from system to system. In someexamples, the predetermined set of positions may be selected to be farenough apart such that, even when the tolerances may be accounted for,they may provide unique coherent noise views or coherent noise states.

Each of the photonics dies may emit respective light beams that afterpassing through optical elements of the system may be incident on thediffusing element with a predetermined beam spread. Additionally, eachof the light beams may have a different angle relative to the diffusingelement due to the spacing of the photonics die and the optical elementsof the system. It may be understood that light beams are a portion oflight that have one or more light rays. The diffusing element may moveto a repeatable set of positions for each light beam so that each lightbeam may pass through the same or a similar set of diffusing elementpositions as each of the other light beams. The diffusing element maymove to a set of positions for an individual light beam so that theindividual light beam will provide a corresponding set of coherent noiseviews or coherent noise states incident on the sample. The diffusingelement may then move to the same or similar set of positions for thelight beam in the next spatial position to provide a corresponding setof coherent noise views or coherent noise states for that light beam,and so forth. It may be understood that although a light beam in a firstposition and a next spatial position may be discussed, the diffuser maychange the coherent noise view for all of the light beamssimultaneously. By providing each light beam with repeatable positions,the signals measured from the different light beams may be averagedtogether so that the signals will approach or in some cases converge tothe correct measured signal and with reduced coherent noise. In otherembodiments, each diffuser position may be visited only once per overallmeasurement and the wavelengths may be used multiple times and once perdiffuser position. Put another way, in some embodiments, the diffuserpositions may be nested within the wavelengths, and in otherembodiments, the wavelengths may be nested within the diffuserpositions.

In some examples, each wavelength can experience the same diffuserposition, but the coherent noise state for each wavelength at a givendiffuser position may be different because the wavelength is different.When mitigating coherent noise, the same or a similar coherent noiseview or coherent noise state may be available at every wavelength orwavelength range emitted by the photonics die. By interrogating thelight at the various angles of the individual light beams, each signalmay include some coherent noise. The signals of the different angles oflight are averaged together, and the coherent noise may approach a zeromean insofar as the signals may approach or converge to the correctsignal or the measured signal without coherent noise. The terms“coherent noise view” and “coherent noise state” may be usedinterchangeably herein.

Even though taken individually, the diffusing element or the phaseshifters may be capable of generating unique coherent noise views at asufficient rate for coherent noise mitigation for the photonicsassembly, each component used individually and without the other mayoccupy too much space and require too much operating power that thecombination of the diffusing element with the phase shifters may bettercomply with the photonics assembly specifications due to space and powerconsiderations. Although the diffusing element and the phase shifterseach may generate unique views, the combination may allow for anincreased number of coherent noise views in a small form factor deviceand/or system.

These and other embodiments are discussed below with reference to FIGS.1-8 . However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these figures is forexplanatory purposes only and should not be construed as limiting.

Directional terminology, such as “top”, “bottom”, “upper”, “lower”,“above”, “below”, “beneath”, “front”, “back”, “over”, “under”, “left”,“right”, and so forth, is used with reference to the orientation of someof the components in some of the figures described below. Becausecomponents in various embodiments can be positioned in a number ofdifferent orientations, directional terminology is used for purposes ofillustration only and is in no way limiting. The directional terminologyis intended to be construed broadly, and therefore should not beinterpreted to preclude components being oriented in different ways.

As used throughout this specification, a reference number without analpha character following the reference number can refer to one or moreof the corresponding references, the group of all references, or some ofthe references. For example, “215” can refer to any one of the photonicsdies 215 (e.g., photonics die 215A, photonics die 215B, etc.), can referto all of the photonics dies 215, or can refer to some of the photonicsdies (e.g., both photonics die 215A and photonics die 215B) depending onthe context in which it is used.

Representative applications of methods and apparatuses according to thepresent disclosure are described in this section. These examples arebeing provided solely to add context and aid in the understanding of thedescribed examples. It will thus be apparent to one skilled in the artthat the described examples may be practiced without some or all of thespecific details. Other applications are possible, such that thefollowing examples should not be taken as limiting.

FIG. 1 illustrates an example photonics assembly 100 which may includean interface 180, a light emitter 110, a detector 130, and a controller140. The interface 180 can include an external surface of a device whichcan accommodate light transmission therethrough. It may be understoodthat the interface 180 may accommodate light transmission in the workingwavelengths. In some examples, the working wavelengths may bewavelengths of light used to measure properties of the sample. Furtherand in some examples, the interface 180 may be opaque to visible lightas visible wavelengths of light may not be used to measure properties ofthe sample. In some examples, the photonics assembly 100 can include anaperture structure 160 including regions that provide differentfunctionalities. In some examples, the regions of the aperture structure160 may include one or more of a transparent region 170, an opaqueregion, a translucent region, a reflective region, a region having adifferent refractive index than surrounding material, any combinationthereof and so forth. The aperture structure 160 may direct and/orcontrol the launch position of the light into the measured sample volume120 and the collection position of the returned light from the measuredsample volume 120. By controlling the location and/or angles of lightentering a measured sample volume 120, the light incident on a measuredsample volume 120, and/or exiting from a measured sample volume 120 canbe selectively configured. As depicted in FIG. 1 , the aperturestructure 160 may be a single interface with multiple apertures,however, the interface may be split into different windows such as alaunch window and one or more collection windows. In some examples, thephotonics assembly may include the photonics die(s), outcouplers,optical components that receive light from the photonics die(s), freespace optics, and so forth, but does not include the sample. Althoughdepicted in FIG. 1 , the measured sample volume 120 is not included inthe photonics assembly 100. The terms “photonics assembly” and“photonics system” may be used interchangeably herein.

While operating the photonics assembly 100, the measured sample volume120 can be located close to, or touching at least a portion of, thephotonics assembly 100, such as the photonics system interface 180. Theone or more light emitters 110 can be coupled to the controller 140. Thecontroller 140 can send a signal (e.g., current or voltage waveform) tocontrol the light emitters 110, which can emit light. The one or morelight emitters 110 may be included in one or more photonics dies 115,which will be discussed in detail herein. Discussions herein mayreference the photonics die(s) 115 as emitting light, though it may beone or more light emitters 110 that are part of the photonics die 115that may be generating light. As such, discussions of the photonics diesemitting light are understood to encompass a light emitter generatinglight, so long as that light emitter is part of the photonics die.

In some examples, the photonics die 115 may emit light, which may bereflected by the outcoupler or mirror 150 included in the photonics die115, and the light may be received by a lens 190. The lens 190 may be afree space lens and, although referred to as a single lens, in someexamples, the lens 190 may be multiple lenses. Additionally, the lens190 may be a single lens that performs multiple functions or may bemultiple lenses that each performs a function such as collimating lightand/or beam steering or beam shaping light received from the photonicsdie 115. The lens 190 will be discussed in further detail herein withreference to FIGS. 2A-8 . The light from the lens 190 may be directed toa diffusing element 135. The diffusing element 135 may move in one ormultiple dimensions and the movement of the diffusing element 135 may bediscrete or continuous. In some examples, a discrete diffusing element135 may step between different positions, while a continuous diffusingelement may vibrate or otherwise continuously move without stopping at aparticular position. In still further examples, the diffusing element135 may be capable of moving to any target position within a desiredrange or may be only physically capable of moving between some fixedpositions. The diffusing element 135 may generate an illuminationprofile of light that is based at least partially on the angle spacingof light received from the lens 190 and the total range of angles oflight incident on the diffuser. The diffusing element will be discussedin further detail with reference to FIGS. 2A-8 .

Depending on the nature of the measured sample volume 120, light canpenetrate into the measured sample volume 120 to reach one or morescattering sites and can return (e.g., reflect and/or scatter back)towards the photonics assembly 100 with a controlled path length. Thereturn light that enters back into the photonics assembly 100 may bedirected, collimated, focused, and/or magnified. The return light can bedirected towards the detector 130. The detector 130 can detect thereturn light and can send an electrical signal indicative of the amountof detected light to the controller 140. In some examples, the detector130 may have optical elements to direct, collimate, focus, magnify, orotherwise shape the return light from the sample.

Additionally or alternatively, the light emitter 110 can optionally emitlight towards the reference (not illustrated in FIG. 1 ). The referencecan redirect light towards optics which may include, but are not limitedto, a mirror, lenses, and/or a filter, and also may redirect lighttowards a sample with known optical properties. The optics may direct,collimate, focus, magnify, or otherwise shape the return light towardsthe detector 130. The detector 130 can measure light reflected from thereference and can generate an electrical signal indicative of thisreflected light for quality purposes. As illustrated in FIG. 1 , thelight emitter 110 emits light toward an outcoupler or mirror 150. Insome examples, the detector 130 may not have unique and/or individualcorresponding pixels for each of the sample and reference signals. Insome examples, the optics may direct the reference light onto the samepixel(s), and the measurements may be time multiplexed. Additionally insome examples, the detector 130 may include one or more pixels, whereeach of the one or more pixels may output a respective signal based onthe light or return light collected by that pixel. Thus, any individualsignal generated by the detector 130 may be representative of a signalor of a reference, depending on which part of the system the light orreturn light striking that pixel is coming from.

The controller 140 can be configured to receive one or more electricalsignals from the detector 130, and the controller 140 (or anotherprocessor) can determine the properties of a sample from the receivedelectrical signals. In some instances, the detector 130 can generatesignals in response to receiving and/or absorbing returned light and, insome examples, may generate at least two electrical signals, where oneelectrical signal can be indicative of returned light, which may bereflected and/or scattered from the measured sample volume 120, andanother electrical signal can be indicative of light reflected/scatteredfrom the reference. Additionally, the detector 130 may be configured totransmit the electrical signals to the controller 140. In some examples,each of the different electrical signals can be a time-multiplexedsignal. For example, each of the different electrical signals for themeasured sample volume and the reference may alternate with one anotherat different points in time. Further to this example, a signal during afirst time period may be representative of the reference, and the signalduring the second time period may be representative of the sample. Inother instances, two or more electrical signals can be received bydifferent detector pixels concurrently and each of the electricalsignals may include information indicative of different lightinformation such as wavelength and intensity.

Generally, photonics systems may be used for sensing and processinglight in electronic systems and devices. Some photonics assemblies maybe used for transmitting light and may be included in an electronicdevice, such as mobile devices, tablets, smart phones, and so forth,which may be used for various purposes such as optical communication,environmental sensing, and/or biometric sensing. Mobile electronicdevices are growing in popularity and these devices are often smallenough to be portable and/or handheld. The architectures of these mobiledevices may include various components, including photonics circuitry,which may affect the size of the device into which it is incorporated.

Because of the increasing emphasis on smaller, more compact electronicdevices, the size and thickness of the components inside of theelectronic device may be limited. In some examples, a particular size ofthe electronic device is targeted and each component within theelectronic device is given a maximum form factor or area that thecomponent(s) may occupy within the electronic device. Accordingly, thephysical configuration of the individual components, such as opticalelements, light emitters, detectors, and an integrated circuit, such asa photonics integrated circuit and/or photonics assembly, may becomeincreasingly important to the form factor of the device. In someexamples, the photonics assembly 100 may be included in various handheldor portable electronic devices such as mobile devices and wearabledevices such as a smart phone, tablet, watch, or any type of device thatmay be worn by a user such as a cuff or bracelet.

FIG. 2A illustrates an optical system. The optical system 200 is arotated view by approximately 90 degrees from the view of the photonicsassembly of FIG. 1 . The optical system 200 may include multiplephotonics dies 215 and output couplers 250. The photonics die mayinclude multiple photonics dies 215, in which each of the individualphotonics dies may be referred to with a separate element number such as215 a, 215 b, 215 c, and so forth. Although eight photonics dies 215 aredepicted in FIG. 2A, any appropriate number of photonics dies 215 may beincluded in the optical system 200. Similarly, each of the individualoutput couplers 250 may be referred to with separate element numbers,and so forth.

In some examples, each of the photonics dies 215 may include multiplelasers and each photonics die 215 may emit over a different wavelengthrange, where the lasers of the corresponding photonics die 215 may emitat unique wavelengths within the wavelength range of the photonics die215. The photonics dies 215 may be integrated into a photonics systemthat may combine all of the emitted light over all of the wavelengthranges into a single waveguide via an optical multiplexer. In someexamples, this light may be split into multiple output waveguides, whereeach waveguide may reach an output coupler 250. In some examples, when asingle laser generates a single wavelength, the single wavelength oflight from the single laser may be routed to all of the output couplers250. Thus, once the single wavelength of light from the single laserreaches free space, there may be multiple simultaneous beams of lightall of which came from the same single laser on the same photonics die.Once a different single laser on a different photonics die emits adifferent wavelength of light, the different wavelength of light maypass through all of the same output couplers and may pass through thesame free space optical system. It may be understood that the number ofphotonics die 215 and the number of output couplers 250 may be differentfrom each other (e.g., there may be either a greater number of photonicsdie 215 than output couplers 250 or a greater number of output couplers250 than photonics die 215).

The optical system 200 may generate a predetermined illumination profilewhich may include controlling both the spatial profile of a light beamand providing a predetermined range of light angles at the diffusingelement 235, which will be discussed in further detail with reference toFIGS. 2B-2D and 3-8 . The range of beam angles incident on the diffusingelement 235 may be a large range of beam angles so that the opticalsystem 200 may reduce noise, and as such may be adjusted accordingly.

As illustrated in FIG. 2A, the optical system 200 may include thephotonics die 215, which may provide light, via the output coupler 250,to the optical subsystem 290. In some examples, all of the light emittedby the photonics dies 215 may be coupled into a single waveguide. Thissingle waveguide may provide light to each of the output couplers 250.In some examples, the light received from the output couplers 250 and bythe optical subsystem 290 may be collimated, directed, and/or deflectedlight at various angles, by the optical subsystem 290 and to themeasured sample volume (not illustrated in FIG. 2A). The opticalsubsystem may include one or more elements to achieve the desiredfunctionality. In some examples, the optical subsystem may include acollimation lens array 292 and a deflection prism array 294. In someexamples, the output coupler 250 may provide light to the collimationlens array 292 of the optical subsystem 290. The collimation lens array292 may collimate the light and direct the light to the deflection prismarray 294, also of the optical subsystem 290. The deflection prism array294 may deflect the light at varying angles depending from which outputcoupler 250 the light was received. The deflected light from thedeflection prism array 294 may be directed to the diffusing element 235and then to the measured sample volume.

In some examples of FIG. 2A, the diffusing element 235 may be positionedin the approximate range of 500 microns to 3 millimeters from themeasured sampling interface. The diffusing element 235 may be locatedclose enough to the measured sample volume, so that the path length maybe controlled. Additionally, the distance between the output coupler 250and the diffusing element 235 may be approximately 2.5-5 millimeters. Asthe light leaves the photonics die 215, the light beam may continue todiverge as it passes through each element of the optical system 200. Insome examples, the beam spread of the collective light beam in thewidest dimension may be between 1-5 microns or less as the light exitsthe photonics die 215, then the beam spread of the collective light beamin the widest dimension may be approximately 100-300 microns whenincident on the collimation lens array 292. The beam spread of thecollective light beam may spread in the widest dimension toapproximately 2.5 mm when incident on the diffuser and then spread inthe widest dimension to approximately 3.0 mm or in the approximate rangeof 2 mm-4 mm when incident on the measured sample volume. Because thecollective light beam spreads as it passes through the optical system200, there is a corresponding range of angles that also changes. Theangle range and beam size at the measured sample volume will bediscussed in further detail with reference to FIGS. 2C and 2D.

In some examples, the photonics assembly may be used to measure a signalintensity from the measured sample volume of FIG. 1 . It may beunderstood that every spatial position may receive every wavelength.When interrogating at one angle launch light and there is one signal onthe detector, the coherent noise may be high for any single launchangle, however, multiple de-correlated measurements may be used to helpidentify the signal. One way to determine the signal intensity in thepresence of coherent noise is by obtaining multiple de-correlatedmeasurements that have the same nominal underlying signal with differentde-correlated coherent noise views. In some examples, the de-correlatedcoherent noise views may be provided by de-cohered light. De-coheredlight is light that does not interfere to provide coherent noise.Providing a target number of unique coherent noise views may be achievedby using phase shifters and a diffusing element together in thephotonics assembly. For example, the phase shifters may provide light tothe output couplers and result in de-cohered light. There are variousways to change the coherent noise pattern on the detector; for example,by changing the wavelength of the light source or by changing thepolarization of the light. Another way to change the coherent noisepattern on the detector may depend on how you launch light onto thesample and this will be discussed in further detail below and withreference to FIGS. 2B-2D and 3-8 .

In one example, two different angles of return light may have the samepath length once the light is reflected by the measured sample volumeand the two signals are measured at a detector (not shown in FIG. 2A).The two signals may have different coherent noise patterns, so eventhough all other factors may be held constant, the two signals will havedifferent intensities since both of the signals are the relevant signalplus some amount of coherent noise. By interrogating various angles,each of which signal will include some coherent noise, once the signalsof the different angles of light are averaged together, the coherentnoise may approach a zero mean and the signals may converge to thecorrect signal or the measured signal without coherent noise. In someexamples, there may be deviations in the path length signal (e.g., in asystem that may be designed to pick up single-scatter events, manyreturned photons may encounter multiple scattering events) alongdifferent paths. In some examples, multiple signals with largely similarsignal characteristics (e.g., similar path length and similar samplecharacteristics), but with sufficiently different angles to createdifferent noise views, and the signals may be averaged and may work toreduce the noise impact.

In FIG. 2A, the optical system may include eight output couplers. It maybe understood that eight output couplers are described for explanatorypurposes only and any number of output couplers may be used. By usingmultiple output couplers 250, the optical system 200 is not as dependenton the diffusing element 235 to generate coherent noise views. Forexample, if the optical system only used one output coupler, then thediffusing element would have to be much larger to diffuse the light tothe desired range of angles and it would be difficult to control themotion of the diffusing element and the repeatability of the diffusingelement positions or set of positions. Although this type of diffusingelement may be used in the optical system with a single photonics die,the movement of the diffusing element would be very sensitive to anychange in position and even a small change would generate a new coherentnoise view, thus making it difficult to revisit the same coherent noiseview from the same position due to the sensitivity. Because the opticalsystem 200 uses multiple output couplers 250, the number of positions towhich the diffusing element 235 may travel may be reduced in comparisonwith a system having a single output coupler. In some embodiments thepositions the diffusing element 235 may move to may be a short distanceapart from one another and in turn, the diffusing element 235 has ashorter full-travel distance than other embodiments with a greaterdistance between positions. In some embodiments, achieving a largernumber of coherent noise views with a greater number of output couplers250 may result in reducing the positions visited by the diffusingelement 235. In this example, the diffusing element 235 may be smallersince the diffusing element 235 may travel to fewer positions.

In some embodiments, the diffusing element 235 may move betweenpositions faster than the wavelengths of light change. For example, thediffusing element 235 may move to or through two or more positionsduring the same length of time that an emitter outputs a singlewavelength of light. Thus, insofar as the diffusing element 235 occupiesmultiple such positions while a particular wavelength of light isemitted, those positions may be said to be “nested” within theparticular wavelength.

In other embodiments, the wavelengths of light may change faster thanthe diffusing element 235 positions change. That is, the diffusingelement 235 may be positioned in a first position during the same lengthof time that the emitter outputs multiple wavelengths. Because thewavelengths may change while the diffusing element 235 may stay in thesame position, the wavelengths may be said to be “nested” within theposition of the diffusing element 235. In this embodiment, each diffuserposition may be visited only once per overall measurement and themultiple wavelengths may be used once per diffuser position. Generally,in some embodiments, the diffuser positions may be nested within thewavelengths, and in other embodiments, the wavelengths may be nestedwithin the diffuser positions.

In some examples, each of the output couplers 250 may be coupled with aphase shifter (not illustrated in FIG. 2A), which may be included in thephotonics die 215 or may be external to the photonics die 215. Phaseshifters may generate unique coherent noise views very quickly, forexample, approximately every 100 picoseconds. Even though the phaseshifters may be capable of generating unique coherent noise views at asufficient rate for coherent noise mitigation for the optical system,the phase shifters may occupy too much space and require too muchoperating power that the combination of the diffusing element 235 withthe phase shifters may better comply with the photonics assemblyspecifications due to space and power considerations.

In some examples, light emitted by the photonics die 215A may providelight to at least an output coupler 250 a that reflects light to theoptical subsystem 290. The optical subsystem 290 may include two opticalcomponents, a collimation lens array 292 and a deflection prism array294. In some examples, the functionality of the collimation lens array292 and the deflection prism array 294 may be combined into a singleoptical subsystem 290. In some examples, the collimation lens array 292may collimate the light received from the output couplers 250 and directthe light to the deflection prism array 294. The deflection prism array294 may direct the light at different angles to the diffusing element235. Generally, prisms are used to redirect light by refraction orinternal reflection. In some examples, the amount a light beam is bentdepends on the apex angle of the prism and the refractive index of theprism material. The angle of incidence of the light may further be usedto adjust the apex angle of the prism.

In FIG. 2A, the output coupler 250 a provides light to the collimationlens array 292, which may collimate the light and direct the light tothe deflection prism array 294. The deflection prism array 294 is thenable to predictably deflect the collimated light at a predeterminedangle and toward the diffusing element 235. The angle at which the lightexits the deflection prism array 294 depends on the position of theoutput coupler 250 from which it is received. For example, lightreceived from the output coupler 250 a may be directed to the diffusingelement 235 at a different angle than the light received from the outputcoupler 250 d, where the light received from the output coupler 250 amay be a steeper angle relative to the deflection prism array 294 thanthe light received from the output coupler 250 d. The deflection prismarray 294 may be designed such that each light beam will be directed toa predetermined position and angle incident on the diffusing element235. Continuing the example, the deflection prism array 294 may directlight to the diffusing element 235. The diffusing element may provide anillumination profile 245 that is illustrated in far-field angle spaceand that is representative of the beam angles of light provided by thediffusing element 235. In some examples of the optical system 200, theillumination profile 245 may have a wide dimension and a narrowdimension. The illumination profile 245 of FIG. 2A illustrates the widedimension. The illumination profile 245 will be discussed in furtherdetail with respect to FIGS. 2B and 2C.

Generally, the diffusing element 235 may be capable of generatingmultiple coherent noise views by moving to multiple locations. However,the more the diffusing element 235 moves, the less reliable andrepeatable each position becomes, thus similar to the phase shifter,even though the diffusing element 235 may sufficiently generate enoughcoherent noise views for the photonics assembly by changing positions,the combination of the diffusing element 235 and the phase shifter inthe photonics assembly provides a more reliable means for mitigatingcoherent noise, while staying within the specifications of the photonicsassembly such as system power, size, number of electrical connectionsavailable, and so forth. Further, due to the ability to control the beamspread and the range of angles of the light between the output couplersto the optical subsystem 290 and between the optical subsystem 290 andthe diffusing element 235, the optical system 200 may reliably generatea predetermined illumination profile of light.

In some examples, the diffusing element 235 may receive light with aninput angle and diffuse the light into a larger output spread of angles.In the example of FIG. 2A, because the diffusing element 235 receiveseight light beams from the eight output couplers 250, the diffusingelement 235 may output eight light beams with eight angle spreads.Additionally, the diffusing element 235 may move to multiple locationsto mitigate coherent noise in the optical system 200. The positioning ofthe diffusing element 235 and the amount by which the diffusing element235 moves to generate a new coherent noise view is determined by thediffuser design; for example, the eight degree angle. In some examples,the diffuser noise may depend at least partially upon the repeatabilityof the diffusing element 235 positioning. In some examples, diffusernoise may be a position-to-position variation in total optical powerthroughput of the system as the diffusing element 235 moves. Diffusernoise may be semi-wavelength independent and sample independent insofaras detailed scattering characteristics may be affected, and may beprimarily determined by the structure/design of the diffusing element235, and secondarily affected by the remainder of the system.

In some examples, each wavelength or wavelength range of light emittedby a corresponding light source may pass through the diffusing element235 at the same set of diffuser states or diffuser positions. That is,the diffusing element 235 may move to a first position for a firstwavelength or wavelength range of light emitted by a first photonicsdie, then the diffusing element 235 may move to a second position forthe first wavelength of light, then a third position, and so forth. Thediffusing element 235 may then move to the same first position for asecond wavelength or wavelength range of light emitted by a secondphotonics die, then move to the same second position, and then to thethird position, and so forth. As a result, the photonics assembly mayinterrogate each wavelength or wavelength range emitted by eachphotonics die at each diffuser position. Should multiple wavelengths oflight experience different diffusing element positions, then thediffuser noise may be intertwined with the wavelength change. It maythen become difficult to verify which part of the signal may beattributed to diffuser noise as opposed to an actual signal change dueto the wavelength change, thus it would be difficult to verify whichpart of the signal is the relevant signal for measurement of the sample.

In FIG. 2A, because there are eight output couplers 250 with a phaseshifter and each of the output couplers provides light, this allows thediffusing element 235 to be eight times slower or move eight fewertimes, thus resulting in less reliance on the diffusing element 235.Although eight photonics dies and eight output couplers are discussedwith reference to FIG. 2A, this is for convenience and ease ofdescription and any appropriate number of photonics dies and anyappropriate number of output couplers may be used in the photonicsassembly.

The diffusing element 235 receives light at a predetermined angle anddiffuses the light and provides an output spread of angles. In theexample of FIG. 2A, the diffusing element 235 receives eight input lightbeams, and in turn, provides eight angle output spreads to produce theillumination profile 245. In some examples, the diffusing element 235may generate an approximately eight degree circle for each light beamreceived from the deflection prism array 294. By overlapping the lightbeams, the diffusing element 235 may produce an illumination profile 245that appears to be a “stripe” of light. Generally, there are fourprimary dimensions which may be varied for path length control, an xdimension, a y dimension, an x angle dimension, and a y angle dimension.The dimension and path length control will be discussed in furtherdetail below and with reference to FIG. 2C and FIG. 2D.

As illustrated in FIG. 2A, the light beams from the output couplers 250may overlap one another to produce the illumination profile 245. Becausethere are eight output couplers, eight overlapping circles areillustrated in FIG. 2A. The eight output couplers 250 are used forexplanatory and descriptive purposes only and any appropriate number ofoutput couplers 250 may be used in the optical system 200. The overlapof the light beams in the illumination profile 245 and the circularshape of the light beams from the diffusing element 235 are at leastpartially dependent on the diffusing element design. The overlap ofangles is a result of the cone shape in angle space of the light beams,because coherent noise mitigation becomes more effective when coveringmost of the angle space of the illumination profile. In some examples, adifferent shaped light beam in angle space may exit the diffusingelement 235 depending on the diffusing element design. In some examples,the diffusing element 235 may diffuse a rectangular light beam in anglespace, which would result in little to no overlap of the diffused lightto cover the specified angle spaces. In some examples, the diffusingelement may be any appropriate shape such as rectangular, square,linear, circular, elliptical, and so forth. In some examples, a circulardiffusing element may generate a circular far-field angle profile.

FIG. 2B illustrates an optical system. FIG. 2B is the same view of thephotonics assembly illustrated in FIG. 1 , which may be referred to asthe side view, and FIG. 2B illustrates the narrow dimension of theillumination profile, whereas FIG. 2A illustrates the wide dimension ofthe illumination profile. Because FIG. 2B is viewed from the side, andalthough only one photonics die 215 and one output coupler 250 aredepicted, there are multiple photonics dies 215 and multiple outputcouplers 250 that cannot be viewed from the side view. The opticalsystem 200 of FIG. 2B may include similarly numbered components as FIG.2A and represent elements with similar features and functionality.

Similar to FIG. 2A, FIG. 2B includes photonics dies 215 that emit lightvia an output coupler 250, toward the collimation lens array 292. Thecollimation lens array 292 may collimate the light and the deflectionprism array 294 may receive the collimated light and deflect it towardthe diffusing element 235. The diffusing element 235 may then providelight to the measured sample volume. In some examples, the lightincident on the measured sample volume may have the illumination profileas discussed with reference to FIG. 2A. Similar to FIG. 2A, thediffusing element 235 may generate an eight degree circle from eachlight beam received from the output coupler 250.

Generally, the optical system 200 of FIG. 2B provides de-phased lightvia the photonics dies 215. The light may be combined on the diffusingelement 235 to generate the predetermined illumination profile, whichmay include the spatial profile of the light as well as thepredetermined angle spread of the light. The narrow dimension of theillumination profile produced in FIG. 2B may provide for path lengthcontrol of the emitted light through the measured sample volume. Shouldthe illumination profile in the narrow dimension vary from thepredetermined value, the optical system may not be able to control thepath length as effectively. The narrow dimension and the wide dimensionof the optical system 200 will be discussed in further detail withreference to FIGS. 2C and 2D.

FIG. 2C is a representation of an illumination profile 245 in anglespace generated by the diffusing element of the photonics assembly. FIG.2C is an illumination profile for the light beam angle spread generatedby the diffusing element of the optical system discussed with referenceto FIGS. 2A and 2B. The optical system may generate the predeterminedangle space or light beam spread of angles of the illumination profile245 incident on a sample. Generating the illumination profile (e.g.,both in the spatial profile and angle space) of the light for thepredetermined angle space allows for effectively mitigating coherentnoise before the light reaches the sample.

Generally, coherent noise mitigation becomes more effective whencovering most of the angle space of the illumination profile. Aspreviously described, the diffusing element may be an eight degreecircular diffuser, such that the light beams may draw out atapproximately eight degrees. In some examples, the diffusing element mayprovide an angle space in a range of 40-60 degrees by 4-15 degrees. Theeight degree circular diffuser is discussed herein for explanatorypurposes only as any appropriate diffuser with any appropriate anglerange may be used in each of the embodiments discussed.

In some examples, the predetermined beam angles exiting from thediffusing element to be incident on the sample may be approximatelyfifty degrees in a first dimension and approximately eight degrees in asecond dimension. Additionally, although fifty degrees by eight degreesis used for explanatory purposes, any angle space may be used. Forexample, the angle space may be in the range of 40-60 degrees by 4-15degrees. The shape of the light beam in angle space is at leastpartially due to the overlapping angles of the light beams as discussedwith reference to FIG. 2A. Additionally, the light beam angles may belarger in one dimension than the other due to the sensitivity of theprofile. In one dimension of angle space, the variation may be lesssensitive when controlling the optical path length due to geometricalconsiderations of the optical system and, in a second dimension of anglespace, the variation may be more sensitive and may have a smaller anglespread.

FIG. 2D is a representation of an illumination profile 255 of the lightbeam shape and size. The beam size incident on the sample may beapproximately 3 mm in a first direction and approximately 0.2 mm in asecond direction. Generally, the larger the illumination profile oflight that is incident on the measured sample volume, the more signalsmay be detected from the measured sample volume, thus it may bedesirable to have a large illumination profile of light that is incidenton the measured sample volume. Similar to the spread of beam angles inangle space, the beam size may be less sensitive to variation in a firstdirection than the other second direction for optical path lengthcontrol.

FIG. 3A illustrates an example optical subsystem in an optical system.The optical system 300 of FIG. 3A includes light system 303, a firstlens 305, a second lens 307, and a diffusing element 310. The opticalsystem 300 illustrates a wide angle range of light provided by thediffusing element when compared to the angle at which light exits thelight system 303. Light system 303 may include one or more photonicsdies and one or more output couplers. The light system 303 may providelight to a first lens 305, which may propagate light along a light path306 to a second lens 307. In some examples, the first lens 305 and thesecond lens 307 may be cylinder lenses to generally collimate the lightinto overlapping beams. It may be understood that the light paths 306,308 and 311 illustrate only the outer light beams that define the outerbounds of an area in which all the light beams may propagate. Forexample, light path 306 may illustrate only two outer light beams, butthere may be multiple overlapping light beams between the two outerlight beams. The outer light beams of light paths 306, 308, and 311illustrate the general shape and direction of the light paths. Thesecond lens 307 may provide light along light path 308 to the diffusingelement 310. Once the light passes through the diffuser, the diffusingelement angle range is significantly larger than the smaller separationof the angles provided by the light system 303.

FIGS. 3B-3C illustrate an example optical system with no diffusingelement and the corresponding far field angular separation of light. InFIG. 3B, the optical system 301 includes a light system 303 thatprovides light along light paths 312 and 313 to a lens 317. The lightmay pass through the lens 317 to the sample volume 320. In someexamples, the lens 317 may be a slow axis collimator. In FIG. 3B, thelight sources of the light system 303 may be separated by a Δx. Thelight from the light sources may propagate along light paths 312 and313, each of which have a beam spread. The light may pass to the lens317, which may collimate the light and the light may then pass to thesample volume 320. In FIG. 3B, the light system 303 may be separatedfrom the lens 317 by a distance 319.

In FIG. 3C, the diagram 302 includes the points 321 and 322, whichillustrate the angular separation of the light beams along Θx, from thelight sources separated by Δx. In some examples, the angular separationbetween the light sources, which is ΔΘ may be the arctangent of thequantity Δx divided by the distance 319.

FIGS. 3D-3E illustrate an example optical system with a diffuser and thecorresponding non-overlapping far field angular separation of centroids.The optical system 343 is similar to the optical system 301 of FIG. 3Bwith the addition of the diffusing element 320. That is, the opticalsystem 343 may include a light system 303 that provides light alonglight paths 312 and 313 to the lens 317. The lens 317 passes the lightto the diffusing element 320 before the light passes to the sample 320.In FIG. 3D, the light sources of the light system 303 may also beseparated by Δx and the light system 303 may be a distance 319 from thelens 317. Although the light depicted in FIG. 3D appears to be similarto the light in FIG. 3B, the diagram 304 of FIG. 3E illustrates thenon-overlapping far field angles after the diffusing element 320.

In FIG. 3E, the diagram 304 includes the beam spread centroids 323 and324, which illustrate the angular separation of the light beams alongΘx, from the light sources separated by Δx. In some examples, theangular separation between the light sources, which is ΔΘ may be thearctangent of the quantity Δx divided by the distance 319. In FIG. 3E,ΔΘ diffuser is greater than ΔΘ and the beam spread also covers a largerarea than that resulting from not using a diffusing element. In FIG. 3E,the light beams may be uncorrelated so long as the far field centroidsare not overlapping with one another.

FIGS. 3F-3G illustrate an example optical system with a diffuser and thecorresponding overlapping far field angular separation of centroids. Theoptical system 345 is similar to the optical system 343 of FIG. 3D andalso includes the diffusing element 320. That is, the optical system 345may include a light system 303 that provides light along light paths 312and 313 to the lens 317. The lens 317 passes the light to the diffusingelement 320 before the light passes to the sample 320. In FIG. 3F, thelight sources of the light system 303 may also be separated by Δx andthe light system 303 may be a distance 319 from the lens 317. Althoughthe light depicted in FIG. 3F appears to be similar to the light in FIG.3D, the diagram 306 of FIG. 3G illustrates the overlapping far fieldangles after the diffusing element 320 as opposed to the non-overlappingfar field angles after the diffusing element 320.

In FIG. 3G, the diagram 306 includes the beam spread centroids 326 and327, which illustrate the angular separation of the light beams alongOx, from the light sources separated by Δx. In some examples, theangular separation between the light sources, which is ΔΘ, may be thearctangent of the quantity Δx divided by the distance 319. In FIG. 3G,ΔΘ diffuser along Θx is greater than ΔΘ and the beam spread also coversa larger area than that resulting from not using a diffusing element. InFIG. 3G, the overlapping far field pattern may be dominated by the lightpassing through the diffusing element 320.

FIG. 4 illustrates an example optical subsystem in an optical system. InFIG. 4 , the optical system 400 is a view of the photonics assemblyillustrating the wide dimension. FIGS. 4-8 will illustrate a similarview of the photonics assembly illustrating the wide dimension and willinclude components similarly positioned to one another within theoptical systems. The optical system 400 may generate a wide launch beamin the wide dimension or in the “stripe” width of the beam shape.Similar to FIGS. 2A and 2B, the optical system 400 of FIG. 4 includesphotonics dies 415, output couplers 450, an optical subsystem 490, and adiffusing element 435.

In some examples, the optical subsystem 490 is a collimation lens array492 and a diverger array 494. The collimation lens array 492 maycollimate the light to provide control of the light beam direction forthe diverger array 494. The diverger array 494 may also be a deflectionarray 494, where the light may be deflected at the appropriate angles tothe diffusing element 435, and thus may be referred to as the deflectionand diverger array herein. Although specific examples of components inoptical subsystems are described, any appropriate optical component maybe used in the photonics assembly to achieve the predeterminedillumination profile to the diffusing element 435 and incident on themeasured sample volume.

FIG. 5 illustrates an example optical subsystem in an optical system. InFIG. 5 , the optical system 500 is a view of a partial photonicsassembly illustrating the wide dimension. Similar to FIGS. 2A and 2B,the optical system 500 of FIG. 5 includes photonics dies 515, outputcouplers 550, an optical subsystem 590 and a diffusing element 535. Theoptical subsystem 590 is a decentered lens array. The decentered lensarray 590 may be a single optical element that combines thefunctionality of the optical components of the optical subsystem of FIG.2A. The decentered lens array 590 may approximately combine thefunctionality of a collimation lens array and the deflection prismarray. The decentered lens array 590 includes a group of lenses that aredecentered from a common axis respective to each lens in the array andwhich may steer the light toward the diffusing element 535.

FIG. 6 illustrates another example of an optical subsystem in an opticalsystem. Similar to the optical system 500 in FIG. 5 , the optical system600 in FIG. 6 is a view of a partial photonics assembly illustrating thewide dimension. The optical system 600 of FIG. 6 includes photonics dies615, output couplers 650, an optical subsystem 690 and a diffusingelement 635.

In the example of FIG. 6 , the optical subsystem 690 is a decenteredtoroidal lens array. The decentered toroidal lens array 690 may be asingle optical element that combines the functionality of the opticalcomponents of the optical subsystem of FIG. 5 . The decentered toroidallens array 690 may approximately combine the functionality of acollimation lens array and a deflection and diverger array. Thedecentered toroidal lens array 690 may collimate light in the narrowdimension of the illumination profile of light and may at leastpartially collimate light in the wide dimension using two differentfocal lengths, and may also steer the light beam in the wide dimensiontoward the diffusing element 635.

FIG. 7 illustrates another example of an optical subsystem in an opticalsystem. In the example of FIG. 7 , the optical subsystem 790 includesphotonics dies 715, output couplers 750, a cylinder lens array 792 and acrossed cylinder lens array 794. The cylinder lens array 792 and thecrossed cylinder lens array 794 may combine the functionality of acollimating array and a deflection array. The cylinder lens array 792may collimate light in a first direction and does not collimate light ina second direction. For example, the cylinder lens array 792 may receivelight from the photonics die 715 and the light may have a fast axis anda slow axis. The fast axis may have light that diverges faster than theslow axis. In some examples, when collimating the light using thecylinder lens array 792, the cylinder lens array 792 may have a shortfocal length in the fast axis direction. Additionally, the crossedcylinder lens array 794 may collimate the light in the second directionand not in the first direction and the crossed cylinder lens array 794may have a longer focal length in the slow axis direction. The crossedcylinder lens array 794 may provide light to the sample 735.

FIG. 8 illustrates another example of an optical subsystem in an opticalsystem 800. In the example of FIG. 8 , the optical subsystem 890includes a fast axis collimator array 892 (e.g., which may be a cylinderarray) and a slow axis focus and steering array 894. The fast axiscollimator array 892 and the slow axis focus and steering array 894 maycombine the functionality of the cylinder lens array and the crossedcylinder lens array of FIG. 7 , along with singlet lenses. The fast axiscollimator array 892 may receive light from the photonics dies 815 thathave a fast axis and a slow axis. The fast axis collimator array 892 maycollimate the light along the fast axis and not the slow axis. The slowaxis focus and steering array 894 may focus the light along the slowaxis and steer the light toward the diffusing element 835. Althoughspecific optical elements have been discussed herein, there may bevarious ways to achieve the appropriate illumination profile incident onthe diffuser and incident on the measured sample volume. In someexamples, additional optical elements may be used between the photonicsdie and the measured sample volume. In some examples, the photonicsassembly may not include a diffusing element. In some examples, thelight beam may be folded in the photonics assembly. In some examples,the light beams may be separated and then allowed for the beam to spreadin angles and in spatial profile and then combine the beams together. Solong as the illumination profile with the predetermined beam angle andspatial profile are incident on the diffuser and are incident on themeasured sample volume, other components of the photonics assembly maybe varied including, but not limited to, the optical components of thephotonics assembly, the positioning of the optical components relativeto one another, the number of light sources, the type of diffusingelement, any combination thereof, and so forth.

FIG. 9 illustrates an example block diagram of an optical device 900,which may in some cases take the form of any of the optical devices asdescribed with reference to FIGS. 1-8 . The optical device can include aprocessor 902, an input/output (I/O) mechanism 904 (e.g., aninput/output device, such as a touch screen, crown or button,input/output port, or haptic interface), one or more optical units 906(e.g., a photonics die which may include a laser diode), memory 908,sensors 910 (e.g., an optical sensing system), and a power source 912(e.g., a rechargeable battery). The processor 902 can control some orall of the operations of the optical device 900. The processor 902 cancommunicate, either directly or indirectly, with some or all of thecomponents of the optical device 900. For example, a system bus or othercommunication mechanism 914 can provide communication between theprocessor 902, the I/O mechanism 904, the optical unit 906, the memory908, the sensors 910, and the power source 912.

The processor 902 can be implemented as any electronic device capable ofprocessing, receiving, or transmitting data or instructions. Forexample, the processor 902 can be a microprocessor, a central processingunit (CPU), an application-specific integrated circuit (ASIC), a digitalsignal processor (DSP), or combinations of such devices. As describedherein, the term “processor” is meant to encompass a single processor orprocessing unit, multiple processors, multiple processing units, orother suitable computing element or elements.

It should be noted that the components of the optical device 900 can becontrolled by multiple processors. For example, select components of theoptical device 900 (e.g., a sensor 910) may be controlled by a firstprocessor and other components of the optical device 900 (e.g., theoptical unit 906) may be controlled by a second processor, where thefirst and second processors may or may not be in communication with eachother.

The I/O mechanism 904 can transmit and/or receive data from a user oranother electronic device. An I/O device can include a display, a touchsensing input surface, one or more buttons (e.g., a graphical userinterface “home” button), one or more cameras, one or more microphonesor speakers, one or more ports, such as a microphone port, and/or akeyboard. Additionally or alternatively, an I/O device or port cantransmit electronic signals via a communications network, such as awireless and/or wired network connection. Examples of wireless and wirednetwork connections include, but are not limited to, cellular, Wi-Fi,Bluetooth, IR, and Ethernet connections.

The memory 908 can store electronic data that can be used by theelectronic device 900. For example, the memory 908 can store electricaldata or content such as, for example, audio and video files, documentsand applications, device settings and user preferences, timing signals,control signals, and data structures or databases. The memory 908 can beconfigured as any type of memory. By way of example only, the memory 908can be implemented as random access memory, read-only memory, Flashmemory, removable memory, other types of storage elements, orcombinations of such devices.

The optical device 900 may also include one or more sensors 910positioned almost anywhere on the optical device 900. The sensor(s) 910can be configured to sense one or more type of parameters, such as, butnot limited to, pressure, light, touch, heat, movement, relative motion,biometric data (e.g., biological parameters), and so on. For example,the sensor(s) 910 may include a heat sensor, a position sensor, a lightor optical sensor, an accelerometer, a pressure transducer, a gyroscope,a magnetometer, a health monitoring sensor, and so on. Additionally, theone or more sensors 910 can utilize any suitable sensing technology,including, but not limited to, capacitive, ultrasonic, resistive,optical, ultrasound, piezoelectric, and thermal sensing technology.

The power source 912 can be implemented with any device capable ofproviding energy to the optical device 900. For example, the powersource 912 may be one or more batteries or rechargeable batteries.Additionally or alternatively, the power source 912 can be a powerconnector or power cord that connects the optical device 900 to anotherpower source, such as a wall outlet.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. Thus, the foregoing descriptions of the specificembodiments described herein are presented for purposes of illustrationand description. They are not targeted to be exhaustive or to limit theembodiments to the precise forms disclosed. It will be apparent to oneof ordinary skill in the art that many modifications and variations arepossible in view of the above teachings.

Although the disclosed examples have been fully described with referenceto the accompanying drawings, it is to be noted that various changes andmodifications will become apparent to those skilled in the art. Suchchanges and modifications are to be understood as being included withinthe scope of the disclosed examples as defined by the appended claims.

What is claimed is:
 1. A photonics assembly, comprising: a set ofsemiconductor light sources, each of the set emitting light; a set ofoutput couplers for receiving light from the set of semiconductor lightsources; an optical subsystem positioned to receive the light from theset of output couplers and shape the light the optical subsystemcomprising: a cylinder lens array positioned to receive the light fromthe set of output couplers, and a crossed cylinder lens array positionedto receive the light from the cylinder lens array; and a diffuserconfigured to provide the light with a coherent noise state of a set ofcoherent noise states on a sample, wherein: the diffuser is operative torepeatedly move between at least a first position and a second position;and by moving repeatedly between at least the first position and thesecond position, the diffuser mitigates coherent noise.
 2. The photonicsassembly of claim 1, wherein: a set of phase shifters is positioned totransmit light to each output coupler of the set of output couplers andgenerates de-cohered light; a beam spread of the light emitted by theset of semiconductor light sources upon exiting the set of semiconductorlight sources is between 1 and 5 microns, and a beam spread exiting thediffuser is in a range of 2-4 mm upon incidence on the sample.
 3. Thephotonics assembly of claim 1, wherein the diffuser is configured toprovide diffused light in an eight degree by eight degree light beam tothe sample.
 4. An optical system, comprising: a set of semiconductorlight sources for emitting light with multiple light beams; a set ofoutput couplers for receiving the light from the set of semiconductorlight sources; and a moveable diffusing element configured to: receivethe light from the set of optical couplers; move to a set of positionsfor each output coupler of the set of output couplers to provide a setof different coherent noise states corresponding to each output couplerof the set of output couplers, and define an illumination profileincident on a sample.
 5. The optical system of claim 4, furthercomprising: an optical subsystem configured to receive the light fromthe set of output couplers; and a set of phase shifters for de-coheringthe light, wherein each light beam of the multiple light beams receivedby the set of output couplers is de-cohered by a corresponding phaseshifter of the set of phase shifters, and each of the set of positionsis repeatable.
 6. The optical system of claim 4, further comprising: afrequency modulator for de-cohering the light provided by the set ofoutput couplers.
 7. The optical system of claim 4, wherein the moveablediffusing element is a circular diffuser.
 8. The optical system of claim4, further comprising: an optical subsystem configured to receive thelight from the set of output couplers, wherein the illumination profileis based at least partially on an angle spacing of light received fromthe optical subsystem.
 9. The optical system of claim 4, wherein theillumination profile is based at least partially on a total range ofangles of light incident on the diffusing element.
 10. The opticalsystem of claim 4, wherein the light emitted by each light source of theset of semiconductor light sources is a different wavelength.
 11. Amethod for mitigating coherent noise, comprising: emitting de-coheredlight from a set of light sources; receiving the de-cohered light at anoptical subsystem that generates a desired illumination profile; anddiffusing the desired illumination profile of the de-cohered light usinga moveable diffuser with coherent noise-unique diffuser states for eachlight beam received from each light source of the set of light sources.12. The method of claim 11, wherein: the illumination profile is basedat least partially on the angle spacing of light received from theoptical subsystem; the coherent noise-unique diffuser states arerepeatable for each light beam; and the total range of angles of lightincident on the diffuser.
 13. The method of claim 11, wherein emittingthe de-cohered light comprises generating a beam spread that is lessthan 4 microns upon exiting the set of light sources.
 14. The method ofclaim 13, wherein diffusing the de-cohered light comprises generating abeam spread of less than 3.2 mm when incident on a sample.
 15. Themethod of claim 11, wherein emitting the de-cohered light comprisesphase shifting the de-cohered light.
 16. The method of claim 11,wherein: each light source of the set of light sources emits a differentwavelength from each other, and diffusing the de-cohered light comprisesgenerating a set of coherent noise views, wherein a same coherent noiseview is generated for each wavelength.